Single dose of AstraZeneca vaccine could cut COVID-19 transmission by 67%

[rooster59]

Single dose of AstraZeneca vaccine could cut COVID-19 transmission by 67%

Paphamon Arayasukawat

 

 

BANGKOK (NNT) - One dose of the Oxford/AstraZeneca vaccine provides sustained protection against COVID-19 for at least three months and cuts transmission of the virus by two-thirds, according to research.

 

Analysis of fresh data from three trials found that the first shot conferred on average 76% protection against symptomatic infections from three weeks until 90 days, and reduced transmission of the disease by 67%.

 

The findings are preliminary, and still under review at The Lancet, but if they stand up to scientific scrutiny would reassure public health officials that prioritising more vulnerable people for a first shot of the Oxford/AstraZeneca vaccine is a sound strategy.

 

While people were originally due to be given two shots of coronavirus vaccines three or four weeks apart, in December the Joint Committee on Vaccination and Immunisation (JCVI), which advises ministers, recommended delaying second doses so more vulnerable people could receive a first shot.

 

Less is known about the impact of spacing out two shots of the Pfizer vaccine.

 

The latest data on the Oxford/AstraZeneca vaccine, drawn from clinical trials in the UK, Brazil and South Africa conducted up until 7 December, show that it may be more effective if the second shot is delayed.

 

Researchers running the trial recorded no evidence for the 76% level of protection waning between three weeks and three months after the first dose. Delaying the second shot for at least three months boosted protection to an average of 82%, they concluded, compared with 62% in the interim trial when volunteers had their shots four weeks apart.

 

The paper suggests vaccine efficacy rose from about 55% when the booster was given no more than six weeks after the first shot, to 82.4% when given more than three months later.

 

-- © Copyright NNT 2021-02-07

 

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[Boomer6969]

And yet several  EU countries have issue restrictions on the use of AZ for elderly patients (over 60). Which is a real bummer for us here.

[Kiujunn]

Long article in Financial Times yesterday.

Short summary: AZ is an incredible mess.

 

The phase 3 clinical studies:

Some people by accident got half first dose

Some people got the second dose much later than originally planned (UK now uses this approach)

Old people were not included, so no data (that's why several EU countries don't use it over 55/60/65)

Because of this mess,  not yet approved in US and Switzerland.  Both want better data.

 

Production:

Glitches at different production sites. They promised 3 billion doses,  that was too much.

Impurities found by regulators.

 

Politics:

They basically vaccinate Britons, not Europeans like Spaniards or Portuguese. Schadenfreude on the British side,  less so on the continent.

Very poor communication. 

 

Details are a lot more complicated,  above is a generalization. 

Some people ask: can we trust this company about quality control? About the safety (AZ says,  it's  DNA vaccine is not integrated into the human genome)?

 

BTW as of today, much reduced efficacy against South Africa variant

[cormanr7]

3 hours ago, Boomer6969 said:

And yet several  EU countries have issue restrictions on the use of AZ for elderly patients (over 60). Which is a real bummer for us here.

Thought the EMA has approved the use of AZ vaccine for 18+ (without age limit), the individual health regulators in many European countries have recommended (not sure if this has to be followed) use for age 18-65.  Belgium has set a max. age of 55 and Switzerland has decided not to approve the AZ vaccine at all -for the moment.https://www.straitstimes.com/world/europe/belgium-like-other-eu-states-limits-astrazeneca-jab

Problem is not with safety but the fact that in the 65+ group in the original trials there were  about 330 people in the vaccinated group and a similar number in the placebo group. In each group, one person was diagnosed with COVID. In other words, these data mean nothing statistically and of course AZ should have known this. They started much later with the age 65+ as supposedly Oxford Univ wanted to be 'ethical' and try it out on lower age groups first. AZ claimed that the fact that antibodies tests in a number of the 65+ group showed similar levels to those of lower age groups indicates that protection does not differ much over the age groups. However, this is indirect evidence.

Two days ago AZ has apparently submitted more data-at least to regulators in the UK- on trials with 65+ people. In addition, their 30,000 people trial in the US should have had interim results (was expected end January). So I would expect the age limit of 65+ to be lifted if results are good and statistics work out (a huge problem with many AZ data).

[Mike Rodik]

what I read or maybe wrongly:  the "vaccine" does not stop you from spreading covid

 

but now suddenly it does ?

 

 

[ourmanflint]

5 hours ago, Kiujunn said:

Long article in Financial Times yesterday.

Short summary: AZ is an incredible mess.

 

The phase 3 clinical studies:

Some people by accident got half first dose

Some people got the second dose much later than originally planned (UK now uses this approach)

Old people were not included, so no data (that's why several EU countries don't use it over 55/60/65)

Because of this mess,  not yet approved in US and Switzerland.  Both want better data.

 

Production:

Glitches at different production sites. They promised 3 billion doses,  that was too much.

Impurities found by regulators.

 

Politics:

They basically vaccinate Britons, not Europeans like Spaniards or Portuguese. Schadenfreude on the British side,  less so on the continent.

Very poor communication. 

 

Details are a lot more complicated,  above is a generalization. 

Some people ask: can we trust this company about quality control? About the safety (AZ says,  it's  DNA vaccine is not integrated into the human genome)?

 

BTW as of today, much reduced efficacy against South Africa variant

The only relevant fact is that it works well. The rest is just waffle

[unblocktheplanet]

Not exactly. Nobody knows yet if vaccinated persons can spread the virus even if they are not themselves infected.

[Caldera]

This looks like a dangerous strategy. Experts in many countries seem to believe that administering just a single dose - or delaying the 2nd dose for a long time - increases the likelihood of the emergence of vaccine resistant strains.

[brianp0803]

Excellent point.

 

Giving as many people the first shot (by delaying the second shot) and getting 67% protection from developing symptoms may create a resistant variant version of the virus.

[Nout]

7 hours ago, Boomer6969 said:

And yet several  EU countries have issue restrictions on the use of AZ for elderly patients (over 60). Which is a real bummer for us here.

us here?...Are you in the EU?

[Kiujunn]

2 hours ago, Mike Rodik said:

what I read or maybe wrongly:  the "vaccine" does not stop you from spreading covid

 

but now suddenly it does ?

 

 

Not sure this is an honest question or you are just an anti-vaxxer.

If it is an honest question,  the answer is:

 

There are different vaccines. 

Biontech/Pfizer and Moderna: it has not been examined yet whether vaccinated persons can still spread the virus by infecting others without getting sick themselves. 

The phase 3 clinical study looked whether vaccinated persons got sick or not, they didn't undergo a PCR test. 

So we just don't know. 

 

AstraZeneca: this PCR was done, so we know that vaccinated persons don't carry the virus. Sho they cannot infect others. 

[Boomer6969]

15 hours ago, Nout said:

us here?...Are you in the EU?

Nope I am here, and I want one of the better vaccines, not the AZ, pushed on the market  after an amateurish validation process and reputed unsuitable for elderly patients.

[cormanr7]

17 minutes ago, Kiujunn said:

Not sure this is an honest question or you are just an anti-vaxxer.

If it is an honest question,  the answer is:

 

There are different vaccines. 

Biontech/Pfizer and Moderna: it has not been examined yet whether vaccinated persons can still spread the virus by infecting others without getting sick themselves. 

The phase 3 clinical study looked whether vaccinated persons got sick or not, they didn't undergo a PCR test. 

So we just don't know. 

 

AstraZeneca: this PCR was done, so we know that vaccinated persons don't carry the virus. Sho they cannot infect others. 

1. There is some further news: it has just been reported that the AZ vaccine is not very effective in protecting against mild disease from the South African variant https://www.reuters.com/article/us-health-coronavirus-astrazeneca-varian/oxford-astrazeneca-covid-shot-less-effective-against-south-african-variant-study-idUSKBN2A60SH. A pretty useless report because of the lack of details but still.

 

2. Interesting further observation; the virus seems to be evolving rapidly, the UK variant has now acquired the E484K mutation from the SA variant https://www.sciencemediacentre.org/expert-reaction-to-document-from-phe-about-the-b-1-1-7-variant-including-reference-to-detection-of-the-e484k-mutation-in-some-b-1-1-7-genomes/.

 

3. Now for some real life effectiveness (as opposed to trial efficacy) for the Pfizer-BioNTEch vaccine in Israel. From an article by  Dvir Aran from the Technion Inst of Technology https://github.com/dviraran/covid_analyses/blob/master/Aran_letter.pdf. Results pertain to 3.1 million people vaccinated once, and 1.8 million having received two doses. Data indicate that number of new positive cases started to decline between ca 12-13 days post dose one. Of the ca 32,000 people that tested positive overall,  789 tested positive at 6 or more days after the second shot, with 27 severe/critical cases (note the individual history of these cases, i.e. when they were effected, underlying diseases, etc is not detailed). Data are divided in two groups: below and over 60 years, respectively,  with the latter having more positive cases immediately after the second shot or 6 days thereafter. 

Author concludes that (within 95% CI boundaries) effectiveness in reducing positive cases is 66-83% for over 60 year olds, 76-85% for below 60 and overall 87-96% in preventing severe disease (so no complete protection against severe disease. That ship has sailed, hardly surprising). Author also briefly discusses the problems and pitfalls of doing studies like this.  

[phantomfiddler]

How about the old "tried and true" method of avoiding people who are coughing their guts up or who have rivers of mucous (aka s**t) running down their face ? Works every time ????

[2009]

3 hours ago, unblocktheplanet said:

Not exactly. Nobody knows yet if vaccinated persons can spread the virus even if they are not themselves infected.

 

Uhm, sorry, try again.

 

How could someone who is not infected spread the virus?

[elliss]

3 hours ago, unblocktheplanet said:

Not exactly. Nobody knows yet if vaccinated persons can spread the virus even if they are not themselves infected.

 

      Correct .

[Letseng]

8 hours ago, cormanr7 said:

Thought the EMA has approved the use of AZ vaccine for 18+ (without age limit), the individual health regulators in many European countries have recommended (not sure if this has to be followed) use for age 18-65.  Belgium has set a max. age of 55 and Switzerland has decided not to approve the AZ vaccine at all -for the moment.https://www.straitstimes.com/world/europe/belgium-like-other-eu-states-limits-astrazeneca-jab

Problem is not with safety but the fact that in the 65+ group in the original trials there were  about 330 people in the vaccinated group and a similar number in the placebo group. In each group, one person was diagnosed with COVID. In other words, these data mean nothing statistically and of course AZ should have known this. They started much later with the age 65+ as supposedly Oxford Univ wanted to be 'ethical' and try it out on lower age groups first. AZ claimed that the fact that antibodies tests in a number of the 65+ group showed similar levels to those of lower age groups indicates that protection does not differ much over the age groups. However, this is indirect evidence.

Two days ago AZ has apparently submitted more data-at least to regulators in the UK- on trials with 65+ people. In addition, their 30,000 people trial in the US should have had interim results (was expected end January). So I would expect the age limit of 65+ to be lifted if results are good and statistics work out (a huge problem with many AZ data).

In the EU this is now a political decision and no longer medical. They bad mouthed AZ vaccine for months. Giving it full approval would be losing face. They rather let this age group fall ill as they can't vaccinate with BNT/Pfizer which is in short supply.

[mommysboy]

3 hours ago, Boomer6969 said:

Nope I am here, and I want one of the better vaccines, not the AZ, pushed on the market  after an amateurish validation process and reputed unsuitable for elderly patients.

 

Malign rubbish.

[brianp0803]

The goal of a vaccine is similar to a country training an army against a specific country’s attack. You cannot stop the country from attacking you, but your trained  army should be able to put down the attack quite quickly. 
 

If the virus does infect the body, it has already developed an attack strategy and will hopefully quickly destroy the invasion before much damage is done.
Ideally, the body’s defense mechanism, after being vaccinated, will quickly defeat the virus before it is multiplied and start spreading.

[NanLaew]

8 hours ago, Mike Rodik said:

what I read or maybe wrongly:  the "vaccine" does not stop you from spreading covid

 

The primary constraint was a vaccine that will prevent recipients from being infected in the first place.

 

8 hours ago, Mike Rodik said:

but now suddenly it does ?

 

Subsequent and longer term testing of the vaccine has focused on a secondary ability to make recipients less infectious to others.

[brianp0803]

The only way to prevent an airborne virus from entering your body would to be to walk around in isolation suit similar to walking on the moon. You must totally isolate your air supply and your eyes from the environment.

 

I believe you are most infectious when you have high amount of virus count in your body. This would be the period before your body has started attacking and destroying the virus.
 

All vaccines act to create an early warning  system for your body that recognizes the virus quickly as dangerous as quickly prepares a defense and quickly starts attacking it. The better the vaccine prepares your body to quickly recognize the dangerous virus and efficiently attack it, then the more efficient the vaccine. If your body quickly attacks the virus, then you will be less contagious and have less symptoms.

[cdemundo]

14 hours ago, Mike Rodik said:

what I read or maybe wrongly:  the "vaccine" does not stop you from spreading covid

 

but now suddenly it does ?

 

 

I don't think anyone who knew what they were talking about said  "the vaccine does not stop you from spreading covid".  

What was said by knowledgable people was that it was unknown if it stopped transmission.

Other vaccine trials were not designed to test if the vaccines stopped transmission.

A person could read that "the vaccine doesn't stop transmission" by reading posts by the semi-informed, you are not wrong about that.

 

[cdemundo]

10 hours ago, phantomfiddler said:

How about the old "tried and true" method of avoiding people who are coughing their guts up or who have rivers of mucous (aka s**t) running down their face ? Works every time ????

Maybe you haven't been following the plot of this little drama.  One of the biggest problems in this pandemic is that the virus can be spread by asymptomatic but infected persons.

Asymptomatic means no coughing up guts, no rivers of mucous, in fact no coughing at all, no mucous running at all.

So the tried and true strategy doesn't work.

[cdemundo]

20 hours ago, Kiujunn said:

Short summary: AZ is an incredible mess.

 

The phase 3 clinical studies:

Some people by accident got half first dose

Some people got the second dose much later than originally planned (UK now uses this approach)

Yes, seems like a real ethnic fire drill.  I don't understand how with so much at stake this was run like a cub scout project, some den mothers were really inattentive.

It is funny how many (me included) have doubts about the development of the Russian and Chinese vaccines when this one seems to be, as you say, an incredible mess and that doesn't get much attention.

[cormanr7]

South Africa has suspended vaccinations with the AZ vaccine as it does not work well against the SA variant

https://www.statnews.com/2021/02/07/south-africa-halts-rollout-of-astrazenecas-covid-19-vaccine-after-shot-falters-against-variant/

[LukKrueng]

16 hours ago, unblocktheplanet said:

Not exactly. Nobody knows yet if vaccinated persons can spread the virus even if they are not themselves infected.

Some experts say the vaccine doesn't stop you from getting infected, but it makes the sickness less severe, so yes, you can still spread the virus

[NanLaew]

51 minutes ago, LukKrueng said:

Some experts say the vaccine doesn't stop you from getting infected, but it makes the sickness less severe, so yes, you can still spread the virus

 

I think it's more of a case that the risk of infection is not a constant and can vary from person to person for reasons of personal physiology and immunity. The vaccine is single-strength, it's the people getting vaccinated that are the mostly unknown quantity. Therefore some may experience some degree of sickness while others won't get sick at all.

 

The jury is still out on who can be infectious or who can shed the virus while being unaware they even have it, regardless of being vaccinated or otherwise.

[Kiujunn]

4 hours ago, cormanr7 said:

South Africa has suspended vaccinations with the AZ vaccine as it does not work well against the SA variant

https://www.statnews.com/2021/02/07/south-africa-halts-rollout-of-astrazenecas-covid-19-vaccine-after-shot-falters-against-variant/

This means,  for the time being SA is not vaccinating at all (they haven't started yet,  anyway).  AZ was their only vaccine,  but even this one was in very limited supply. And it didn't look like mass vaccinations would start really soon. 

https://www.bbc.com/news/world-africa-55675806

(5 days ago)

 

So they follow the common approach "wait and see".

Meanwhile,  in Tyrol  - the place from where skiers spread Covid19 all over Europe last spring - they have 230 cases of the SA variant and skiing is allowed.

Neighboring Italy opened completely. 

Neighboring Germany is locked down,  trips  to Italy and Tyrol are promoted on TV and social media. 

German epidemiologist Klaus Stoehr (worked for the WHO during SARS) is calling for a national committee to fight Covid19 in the long run.

"In the long run, we are all dead" (i admit this quote is out of context).

 

I am glad I am in Asia. 

[2009]

20 hours ago, elliss said:

 

      Correct .

 

Ok, please explain to my chimplike mind: how exactly does a person who is not infected with something spread it?

[elliss]

4 hours ago, 2009 said:

 

Ok, please explain to my chimplike mind: how exactly does a person who is not infected with something spread it?

 

    I would not take a vaccine , that has not been tried and tested , on chimps..555

     Pandemic panic rules ...